CoOx Nano-clusters anchored onto 10-membered ring of Silicate-1 boost propane dehydrogenation

Cobalt-zeolites catalysts for propane dehydrogenation (PDH) suffer from low activities on the confined Co sites in zeolites or poor stabilities on the CoOx species in presence of hydrogen. In this work, we synthesize a unique Co structure with (≡Si-O)2Co(≡Si-O)2…CoO clusters (smaller than 2 nm) onto desilicated Silicate-1 via impregnation-dry gel transformation approach. This structure leads to a high C3H6 formation rate of 34 mmol gcat-1 h-1 as well as a low deactivation rate of 0.0116 h-1 at specific conditions (100% propane, 550 °C, 5.0 h-1, 72 h), outperforming currently reported Co-based catalysts in terms of maximum activity and stability. The integrated differential phase-contrast scanning transmission electron microscopy (iDPC-STEM) and extended X-ray absorption fine structure (EXAFS) measurements confirm that CoO clusters bond with the O atoms adjacent to the tetrahedrally coordinated Co single sites anchored on the 10-membered ring of Silicate-1. The electron-negativity property of ((≡Si-O)2Co(≡Si-O)2…CoO) species facilitates the adsorption of H* from C3H8 and the following dehydrogenation steps, and thus enhancing the overall activity, while its lower formation energy ensures the higher catalyst stability even in presence of hydrogen atmosphere. The designed Co-based catalyst offers great potential for taking the combined advantages of Co singles atoms as well as CoOx clusters for high-performance PDH.